Refrigeration & Air Conditioning Mechanic Red Seal · Question
A large commercial refrigeration unit's expansion valve external equalizer line is observed to be restricted or plugged. What effect will this likely have on the TXV's operation?
A restricted external equalizer line means the pressure on the bottom of the TXV diaphragm (evaporator outlet pressure) is sensed as lower than actual, causing
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Question: A large commercial refrigeration unit's expansion valve external equalizer line is observed to be restricted or plugged. What effect will this likely have on the TXV's operation?
Answer options:
- The TXV will open too wide, leading to evaporator flooding.
- The TXV will shut down completely, starving the evaporator. ✅ The TXV will try to close down too much, leading to a starved evaporator and high superheat.
- It will have no effect, as the internal equalizer compensates.
Correct answer: The TXV will try to close down too much, leading to a starved evaporator and high superheat.
Explanation: A restricted external equalizer line means the pressure on the bottom of the TXV diaphragm (evaporator outlet pressure) is sensed as lower than actual, causing the valve to starve the evaporator by closing too much. This leads to high superheat and reduced cooling capacity. This is an important distinction for external equalizer TXVs.
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Question explanations
- Which of the following refrigerants is a hydrofluorocarbon (HFC) and has a high ozone depletion potential (ODP
- Which component is responsible for compressing the refrigerant vapour to a high pressure and temperature?
- According to the Canadian Electrical Code (CEC), what is the minimum required working clearance in front of el
- What is the main operating characteristic difference between a fixed orifice (capillary tube) and a Thermostat
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